我的vb串口代码

'------------------COM ---------- Dim COM_NO As Byte Dim DELAY As Long Dim TXCNT As Long Dim RXCNT As Long Dim TOTALTX As Long '----------------------------- Private Sub Form_Load() On Error GoTo err '-------------CHECK THE COM------------- Dim i As Integer For i = 1 To 16 MSComm1.CommPort = i On Error Resume Next MSComm1.PortOpen = True If err.Number = 0 Then COM_NO = i Else MSComm1.PortOpen = False End If Next i '----------------------------------------- MSComm1.CommPort = COM_NO If MSComm1.PortOpen = True Then MSComm1.PortOpen = False If MSComm1.PortOpen = False Then MSComm1.Settings = "9600,n,8,1" MSComm1.RThreshold = 1 '******核心语句，去掉则无法触发 'MSComm1.SThreshold = 1 '发送缓冲区中允许的最小字符数触发 MSComm1.OutBufferSize = 10 MSComm1.InputLen = 0 '***********CHANGEED MSComm1.InputMode = comInputModeBinary '1-- 'MSComm1.InputMode = comInputModeText MSComm1.PortOpen = True '--------------------------------- End If If MSComm1.PortOpen = False Then MsgBox "串口打开失败，请检查": End Exit Sub err: MsgBox "串口错误" End Sub Private Sub MSComm1_OnComm() Dim Instring As Byte Dim ins As String Dim RE_BUF As Double On Error GoTo err Select Case MSComm1.CommEvent Case comEvReceive Dim InByte,i As Integer InByte = MSComm1.Input For i = 0 To UBound(InByte) Instring = (InByte(i)) Next End Select If Instring = 255 And FUNC = "CHOSE" Then MAIN_PWM = True: MsgBox "PWM设置成功": Exit Sub If Instring < 5 And FUNC = "CHOSE" Then If Instring = 1 Then CH1 = True: Form5.Text1.Text = Form5.Text1.Text + "通道1 OK" If Instring = 2 Then CH2 = True: Form5.Text1.Text = Form5.Text1.Text + "通道2 OK" If Instring = 3 Then CH3 = True: Form5.Text1.Text = Form5.Text1.Text + "通道3 OK" If Instring = 4 Then CH4 = True: Form5.Text1.Text = Form5.Text1.Text + "通道4 OK" Exit Sub Else End If Instring = Hex(Instring) If Instring > 10 And Instring < 18 Then If Instring = 11 Then CH1_STEP = 1 If Instring = 12 Then CH1_STEP = 3 If Instring = 13 Then CH1_STEP = 2 If Instring = 14 Then CH1_STEP = 4 If Instring = 15 Then CH1_STEP = 6 If Instring = 16 Then CH1_STEP = 5 If Instring = 17 Then CH1_STEP = 7 If CH1_STEP > 0 Then Form8.Show If CH1_STEP > 0 Then Form8.Command1.Value = True Exit Sub Else End If If Instring > 20 And Instring < 28 Then If Instring = 21 Then CH3_STEP = 1 If Instring = 22 Then CH3_STEP = 3 If Instring = 23 Then CH3_STEP = 2 If Instring = 24 Then CH3_STEP = 4 If Instring = 25 Then CH3_STEP = 6 If Instring = 26 Then CH3_STEP = 5 If Instring = 27 Then CH3_STEP = 7 If CH3_STEP > 0 Then Form10.Show If CH3_STEP > 0 Then Form10.Command1.Value = True Exit Sub Else End If If Instring > 30 And Instring < 38 Then If Instring = 31 Then CH2_STEP = 1 If Instring = 32 Then CH2_STEP = 3 If Instring = 33 Then CH2_STEP = 2 If Instring = 34 Then CH2_STEP = 4 If Instring = 35 Then CH2_STEP = 6 If Instring = 36 Then CH2_STEP = 5 If Instring = 37 Then CH2_STEP = 7 If CH2_STEP > 0 Then Form9.Show If CH2_STEP > 0 Then Form9.Command1.Value = True Exit Sub Else End If If Instring > 40 And Instring < 48 Then If Instring = 41 Then CH4_STEP = 1 If Instring = 42 Then CH4_STEP = 3 If Instring = 43 Then CH4_STEP = 2 If Instring = 44 Then CH4_STEP = 4 If Instring = 45 Then CH4_STEP = 6 If Instring = 46 Then CH4_STEP = 5 If Instring = 47 Then CH4_STEP = 7 If CH4_STEP > 0 Then Form11.Show If CH4_STEP > 0 Then Form11.Command1.Value = True Else End If Exit Sub err: MSComm1.InBufferCount = 0 Call cominit End Sub '发送函数做的是全局函数，调用的form2的com控件 Public Function RS232_SEND(SEND_COUNT As Integer) If Form2.MSComm1.PortOpen = False Then Form2.MSComm1.PortOpen = True Form2.MSComm1.OutBufferCount = 0 'Debug.Print "start" Dim i For i = 1 To SEND_COUNT Dim cc(0) As Byte cc(0) = RS232_SEND_BUFFER(i - 1) Form2.MSComm1.Output = cc Debug.Print RS232_SEND_BUFFER(i - 1) Next i 'Debug.Print "end" End Function

串口会出现假死机的现象
初步怀疑是软体原因
我在接收程序中作了修改
一旦开始接收就把MSComm1.RThreshold = 0 暂时停止接收触发

如果接收出错则清空接受区，重新初始化串口

接收缓冲区设置为40，inputleng设置为1

看效果如何

如果还不行就考虑是下位机pic单片机的问题

（编辑：李大同）

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